Integrated flight control indicator

ABSTRACT

An integrated flight control indicator for providing visual information indicative of aircraft flight parameters has a sky arc and an earth arc which are visually distinguishable from one another. The sky arc and the earth arc cooperate to generally define a circle wherein the relative lengths of the sky arc and the earth arc indicate the pitch of the aircraft. A horizon line extends approximately between the two intersections of the sky arc and the earth arc so as to provide a visual indication of the roll of the aircraft. Other indicia are provided for indicating radar or barometric altitude, vertical speed, heading, ground track, minimum altitude break, etc. Thus, the present invention provides a visual indication suitable for use in instrument panel displays, heads-up display, and helmet-mounted displays.

FIELD OF THE INVENTION

The present invention relates generally to aircraft instrumentation andmore particularly to an integrated flight control indicator forproviding visual information indicative of aircraft flight parameterswhich is suitable for use in control panels, heads-up displays, andhelmet-mounted displays. The integrated flight control indicator of thepresent invention is specifically designed to remain functional evenwhen reduced in size, so as to be compatible with helmet-mounteddisplays and the like, and so as to provide minimal obstruction to apilot's view. No alpha-numerics are required for basic instrumentflight, thus facilitating such reduction in size.

BACKGROUND OF THE INVENTION

Flight control indicators for providing visual information indicative ofaircraft flight parameters are well known. Such flight controlindicators include artificial horizons (attitude indicators), turncoordinators, heading and ground track indicators, compasses, pitchindicators, radar and barometric altitude indicators, and a variety ofother flight control instruments. Such flight control indicators providethe pilot with critical information regarding the attitude and positionof the aircraft so as to facilitate flight safety, even during adversevisual conditions.

As those skilled in the art will appreciate, it is not uncommon to relyupon such instrumentation to properly perform critical flight maneuvers.For example, when the horizon cannot be seen, such as during conditionsof low visibility, the pilot's senses cannot distinguish between abanked turn and straight and level flight. In either case, gravityand/or centrifugal force act upon the pilot in a direction normal to thepilot's seat, thus potentially leading the pilot to believe that theaircraft is flying straight and level even when the aircraft is in abanked turn. As those skilled in the art are aware, relying solely uponthe pilot's senses has, in the past, led to fatal aircraft crashes.

It is also known to integrate a plurality of such flight controlindicators in an attempt to provide a compact and easily read device.U.S. Pat. Nos. 5,250,947; 5,248,968; 5,212,480; 5,136,301; 4,903,017;4,626,851; 4,583,094; 4,563,742; 4,326,189; 4,419,079; 4,283,705;4,040,005; 3,970,829; 3,520,994; 3,500,413; 3,162,834 and 2,685,226disclose examples of such integrated devices.

As those skilled in the art will appreciate, there has been a definitetrend in the art during recent years toward the development of heads-updisplays wherein the flight control indicators are projected in such amanner as to allow the pilot to view such indicators without loweringhis head. Further, it is desirable to provide an integrated heads-upflight control indicator wherein the important individual indicators areintegrated into a single display for quick reference.

When using such a heads-up display, the pilot's attention is notmomentarily distracted from the field of view. Such momentarydistraction is particularly undesirable in military situations, whereinit is critical to continually observe one's surroundings. It is alsoadvantageous to utilize such a heads-up display in many civilianapplications. For example, when flying any aircraft at low altitudes, itis very desirable to maintain continuous surveillance of the terrain soas to avoid a collision with upstanding structures, i.e., buildings,radio towers, etc., and natural formations, i.e., mountains, trees, etc.Even the momentary distraction associated with checking the instrumentpanel has the potential for causing a catastrophe.

Although some of the displays disclosed by the cited prior art patentsmay appear to be suitable for use as flight control indicators forheads-up displays, it is important to recognize that a properly designedheads-up display will exhibit certain desirable characteristics, whichare lacking in such contemporary devices. Most importantly, a properlydesigned heads-up display will be simple in construction such that itdoes not distract the pilot from normal viewing through the aircraftcanopy or helmet visor and such that the desired information displayedthereby may readily be ascertained. Thus, the indicator must contain theappropriate number of elements which are required to convey the desiredinformation. Any extraneous elements merely unnecessarily complicate thedisplay and distract attention away from those elements which providecrucial information, as well as distract attention away from normalobservation through the canopy or helmet visor.

In this respect, it is desirable that the number and configuration ofelements be optimized to most effectively and efficiently convey thedesired information. It is thus also desirable that elements of theflight control indicator serve a plurality of different indicatingfunctions, where possible.

SUMMARY OF THE INVENTION

The present invention specifically addresses and alleviates theabove-mentioned deficiencies associated with the prior art. Moreparticularly, the present invention comprises an integrated flightcontrol indicator for providing useful information indicative ofaircraft flight parameters. In a first embodiment, the integrated flightcontrol indicator comprises a sky arc and an earth arc visuallydistinguishable from the sky arc. The sky arc and the earth arccooperate to generally define a circle. The relative lengths of the skyarc and the earth arc indicate the pitch of the aircraft.

The sky arc has a length greater than the length of the earth arc toindicate pitch up and the earth arc has a length greater then the lengthof the sky arc to indicate pitch down.

The sky arc and the earth arc, along with all other indicia which formthe integrated flight control indicator of the present invention,provide a visual indication suitable for use in instrument paneldisplays, heads-up displays, and helmet-mounted displays. As thoseskilled in the art will appreciate, the sky arc, earth arc, and otherindicia may be formed by a variety of different means. For example, acathode ray tube (CRT) may be utilized to form the sky arc, earth arc,and other indicia. The CRT may be used directly in an instrument paneldisplay, or may be reflected or projected to form a heads-up display orhelmet-mounted display. The integrated flight control display of thepresent invention may be formed by various different computer controlledprojection means.

The sky arc and the earth arc are preferably formed of different colorsso as to be visually distinguishable from one another. Similarly, thevarious other indicia, as discussed below, may be formed of variousdifferent colors so as to facilitate their being distinguished from oneanother. Alternatively, the sky arc and the earth arc are formed ofdifferent line thicknesses so as to be visually distinguishable from oneanother and the other indicia are formed to be distinguishable in asimilar manner.

The integrated flight control indicator of the present inventionpreferably further comprises an aircraft symbol which is locked inrelative orientation to the aircraft centerline, such that the sky arcand earth arc rotate relative thereto during roll maneuvers. Theaircraft symbol preferably further comprises a pitch dot formedgenerally in the center thereof so as to facilitate a more preciseindication thereby.

The integrated flight control indicator preferably further comprises ahorizon line extending approximately between the two intersections ofthe sky arc and the earth arc, so as to provide a visual indication ofthe pitch of the aircraft. The horizon line will be positioned above theaircraft symbol when the airplane is in a nose-down attitude and will bebelow the aircraft symbol when the aircraft is in a nose-up attitude.The horizon line will be superimposed over the pitch dot when theaircraft is in a level or zero pitch attitude. Thus, the combination ofthe sky arc, earth arc, and horizon line, taken together, provide aninstant, easily discernible, indication of the roll and pitch attitudesof the aircraft. This information is provided in a format which isimmediately accessible by a pilot in a manner which is clear andunambiguous.

The integrated flight control indicator preferably further comprisesbank angle markers extending a short distance radially inward from thetwo intersections of the sky arc and the earth arc to the two ends ofthe horizon line. The angle between the bank angle markers and thehorizon line varies with the pitch of the aircraft such that duringlevel flight the bank angle markers are co-linear with the horizon line,during pitch down the bank angle markers angle up from the horizon line,and during pitch up the bank angle markers angle down from the horizonline. Thus, the bank angle markers provide a further visual indicationof the pitch angle of the aircraft, thereby making pitch angle even morereadily discernible.

The bank angle markers also provide a marker or index point for anumerical display of the bank angle of the aircraft. The numerical bankangle display is preferably deactivated by default, so as to reduceclutter. It must specifically be activated by the pilot in order to bedisplayed. The numerical display of the bank angle of the aircraft isformed proximate one of the bank angle markers. The bank angle marker bywhich the numerical display of the bank angle is formed is thatparticular bank angle marker corresponding to the lowermost wing of theaircraft. This provides an instantly discernible and precise indicationof the roll angle or the angle at which the aircraft is banked and alsoprovides a further visual cue as to which wing is lowermost.

A numerical display of the pitch angle of the aircraft is preferablydisposed proximate the circle formed by the sky arc and the earth arc,preferably immediately to the right thereof. The numerical display ofthe pitch angle preferably comprises a tape display wherein a series ofsequential pitch angles are configured as a reel of tape and the numbersscroll past an index mark which points to the pitch angle correspondingto that of the aircraft pitch, in the manner of a contemporary tapedisplay. The tape display may optionally be disabled, so as to reduceclutter, i.e., simplify the integrated flight control indicator.

The integrated flight control indicator of the present inventionpreferably further comprises an earth line formed below the aircraftsymbol and generally parallel to the horizon line. A numerical displayof the altitude of the aircraft is preferably formed upon the earthline. The numerical display of altitude is optionally followed by theletter R when radar altitude is selected and letter B when barometricaltitude is selected. Those skilled in the art will appreciate thatvarious other indicia may alternatively be utilized, so as to indicatethe selection of either radar or barometric altitude.

A vertical rate indicator symbol is formed ntermediate the earth lineand the aircraft symbol. According to the preferred embodiment of thepresent invention, the vertical rate indicator symbol comprises aninverted V which moves vertically between the earth line and theaircraft symbol along a vertical line extending therebetween at a ratewhich is representative of the vertical climb or descent rate of theaircraft.

The distance between the aircraft symbol and the vertical rate indicatorsymbol is preferably indicative of the aircraft's position within pilotpreset altitude limits. Thus, an upper attitude limit is indicated bythe point of the vertical rate indicator symbol being disposed upon thebottom of the earth arc (or the sky arc, if the aircraft is an invertedorientation) and a lower altitude limit is indicated by the earth linecontacting the aircraft symbol. A further desired minimum altitude isindicated by the point of the vertical rate indicator symbol contactingthe aircraft symbol. Thus, upper and lower predetermined altitudelimits, as well as a desired minimum altitude, are indicated by therelative positions of the aircraft symbol, the earth line, and thevertical rate indicator symbol, as discussed in further detail below.

A break-altitude symbol is optionally formed within the circle definedby the sky arc and the earth arc, preferably overlaying the aircraftsymbol to indicate that the aircraft has descended below a presetminimum altitude. The break-altitude symbol preferably comprises aflashing X, preferably red, so as to immediately draw the attention ofthe pilot. The break-altitude symbol may be utilized to indicate thatthe aircraft has descended below a safe or authorized altitude, and thusrequires immediate action from the pilot. The break-altitude symbolpreferably remains in place and continues to flash until the aircraftascends above the preset minimum altitude. Alternatively, thebreak-altitude indicator may be manually disabled.

Additionally, a heading and ground track indicator is preferably formedproximate the circle formed by the sky arc and the earth arc, preferablyimmediately thereabove. The heading and ground track indicatorpreferably comprises a comparatively small circle disposed proximate thecomparatively larger circle formed by the sky arc and the earth arc. Theheading and ground track indicator preferably comprises an indication ofnorth formed thereon and an indication of aircraft heading relative tonorth formed thereon, as well. According to the preferred embodiment ofthe present invention, a numerical display of the aircraft heading isformed within the comparatively small circle of the heading and groundtrack indicator and the indication of north preferably comprises anarrow or index mark extending radially outward from the heading andground track circle. Preferably, the letter N is formed proximate thearrow. Optionally, an indication of the other compass directions, e.g.,south, east, and/or west, are likewise provided.

The indication of the aircraft's heading preferably comprises an arrowor index mark formed within the heading and ground track circle anddirected radially outward. The heading and ground track displaypreferably further comprises a numerical display of the differencebetween the aircraft heading and the aircraft ground track. Thenumerical display of the difference is preferably formed proximate thenumerical display of the aircraft heading, preferably therebelow. A plusformed to the left of the difference display indicates that the numberdisplayed must be added to the aircraft heading to obtain aircraftground track and a minus displayed to the left of the numericaldifference indicates that the number must be subtracted from theaircraft heading to obtain the aircraft ground track.

The indication of north preferably comprises a north-south line definedby first and second diametrically opposed index marks or outwardlypointing arrows extending radially from the head and ground trackcircle. The first index mark has an N formed proximate thereto and thesecond index mark has an S formed proximate thereto to indicate thenorth and south directions, respectively. The indication of the aircraftheading preferably comprises a index mark or outwardly pointing arrowformed within the heading and ground track circle. The north-south lineis rotatable around the heading and ground track indicator circle andthe heading index is stationary relative to the ground track indicatorcircle, so as to provide an indication of heading. The rate that thenorth-south line rotates around the heading and ground track indicatorcircle is proportional to aircraft's turn rate, so as to provide avisual indication thereof. The north-south line also provides a visualindication of north, i.e., provides compass directions.

In a second embodiment of the present invention, terrainfollowing/avoidance is facilitated. A flight path marker, preferablyconfigured generally similar to the aircraft symbol of the firstembodiment of the present invention, provides an indication of theflight path. The aircraft is on the desired flight path when theaircraft symbol, which is locked to the aircraft centerline, is alignedwith the flight path marker. The pilot can easily adjust the flight pathof the aircraft to the desired flight path by merely moving the aircraftsuch that the stationary aircraft symbol aligns with the flight pathmarker.

For example, if the flight path marker is below and to the left of thestationary aircraft symbol, then the pilot merely maintains a nose-downattitude and banks to the left until the stationary aircraft symbol isaligned with the flight path marker. Thus, the pilot can easily maintainthe aircraft on a course in accordance with terrain following/avoidanceequipment.

According to a third embodiment of the integrated flight controlindicator of the present invention, Instrument Landing System (ILS)symbology is added to terrain following/avoidance symbology, so as tofacilitate an instrument landing approach. The instrument landingsymbology comprises a heading and glide slope indicator which, in amanner similar to the flight path marker of the second embodiment of thepresent invention, provides a visual indication of the aircraft headingand altitude relative to the desired glide slope. According to the thirdembodiment of the present invention, the heading and glide slopeindicator comprises a circle which is comparatively smaller than thecircle defined by the sky arc and earth arc and which is constrained tostay within the circle defined by the sky arc and earth arc and isdamped to prevent erratic motion thereof. Thus, during an ILS approach,the pilot merely maneuvers the aircraft such that the stationaryaircraft symbol remains generally centered within the ILS flight pathmarker in a fashion similar to that of the terrain following/avoidanceprocedure discussed above.

A minimum altitude marker and numeric display are preferably alsoprovided, along with a numeric display of aircraft altitude.

According to the third embodiment of the present invention, the pitchnumeric tape of the first and second embodiments thereof is replacedwith an angle-of-attack numeric tape.

Thus, the present invention provides an integrated flight controlindicator for providing visual information indicative of aircraft flightparameters. The present invention is suitable for use in control panels,heads-up displays, and helmet-mounted displays. The integrated flightcontrol indicator provides information regarding crucial flight controlparameters in a manner which is readily ascertainable, clear, andunambiguous and which is particularly well suited for use in projectedindicators such as heads-up and helmet-mounted displays.

These, as well as other advantages of the present invention will be moreapparent from the following description and drawings. It is understoodthat the changes in the specific structure shown and described may bemade within the scope of the claims without departing from the spirit ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first embodiment of the integrated flight controlindicator of the present invention for an aircraft flying straight andlevel on a heading of 310 degrees with a ground track of 308 degrees at450 feet of altitude as measured by the aircraft's barometer altimeter;

FIG. 2 shows the integrated flight control indictor of FIG. 1 for anaircraft banking to the right at 36 degrees and pitched down at -40degrees on a heading of 50 degrees with a ground track of 53 degrees andflying at 600 feet according to the aircraft's radar altimeter;

FIG. 3 shows the sky arc portion of the integrated flight controlindicator of FIGS. 1 and 2;

FIG. 4 shows the earth arc portion of the integrated flight controlindicator of FIGS. 1 and 2;

FIG. 5 shows the aircraft symbol and pitch dot of the integrated flightcontrol indicator of FIGS. 1 and 2;

FIG. 6 shows the horizon line of the integrated flight control indicatorof FIGS. 1 and 2, having pitch-angle index markers angled upwardlytherefrom;

FIG. 7 shows the bank angle numeric display indicating a bank angle of36 degrees;

FIG. 8 shows the pitch numeric tape indicator of the integrated flightcontrol indicator of FIGS. 1 and 2;

FIG. 9 shows the earth line, radar altitude numeric display, andvertical rate indicator of the integrated flight control indicator ofFIGS. 1 and 2;

FIG. 10 shows the minimum altitude break symbol;

FIG. 11 shows the heading and ground track indicator of FIGS. 1 and 2;

FIG. 12 shows a second embodiment of the integrated flight controlindicator of the present invention for an aircraft banking at 36 degreesto the right and pitched down at -40 degrees, having a heading of 50degrees and a ground track of 53 degrees and also showing a stationaryaircraft symbol locked to the aircraft centerline and a flight pathmarker to the left of and lower than the stationary aircraft symbol, soas to provide an indication of the deviation of the aircraft from thedesired flight path;

FIG. 13 shows the stationary aircraft symbol of FIG. 12;

FIG. 14 shows the flight path marker of FIG. 12;

FIG. 15 shows the pitch numeric tape of FIG. 12;

FIG. 16 shows a third embodiment of the integrated flight controlindicator of the present invention for an aircraft having zero degreesof bank and descending at the desired rate, having an angle-of-attack of13 degrees, on a heading of 50 degrees and ground track of 53 degrees,passing through 2,150 feet as measured by the barometric altimeter, andindicating a minimum approach altitude of 1,200 feet barometric;

FIG. 17 shows the Instrument Landing System symbol of FIG. 16 includingthe stationary heading and glide slope indicator, the moving flight pathmarker, the minimum altitude indicator, and the rate indicator;

FIG. 18 shows the angle-of-attack tape of FIG. 16;

FIG. 19 shows the heading and glide slope indicator of FIG. 16;

FIG. 20 shows an integrated flight control indicator having an optionalair speed indicator added thereto; and

FIG. 21 shows an integrated flight control indicator having an optionalintegrated fire control indicator added thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The detailed description set forth below in connection with the appendeddrawings is intended as a description of the presently preferredembodiments of the invention and is not intended to represent the onlyforms in which the present invention may be constructed or utilized. Thedescription sets forth the functions and the sequence of steps forconstructing and operating the invention in connection with theillustrated embodiments. It is to be understood, however, that the sameor equivalent functions and sequences may be accomplished by differentembodiments that are also intended to be encompassed within the spiritand scope of the invention.

The integrated flight control indicator of the present invention isillustrated in FIGS. 1-21 which depict three presently preferredembodiments of the invention. FIGS. 1-11 illustrate the first embodimentof the present invention wherein an aircraft symbol having a pitch dotis locked to aircraft centerline. The second embodiment of the presentinvention is illustrated in FIGS. 12-15 wherein the stationary aircraftsymbol comprises a generally horizontal line having a V-groove formed atthe center thereof and utilizing a flight path marker to facilitateflight along a desired flight path. The third embodiment of the presentinvention is illustrated in FIGS. 16-19 wherein a stationary heading andslope indicator cooperates with a moving flight path marker tofacilitate use with instrument landing Systems.

Referring now to FIGS. 1-11, the first embodiment of the presentinvention comprises a sky arc 10, and earth arc 12 cooperating with thesky arc 10 so as to define a circle, and an aircraft symbol 14 having anoptional pitch dot 16 preferably centered therein. The aircraft symbol14 (best shown in FIG. 5) preferably comprises a circle 18 having first20 and second 22 lines extending horizontally therefrom and third line24 extending vertically therefrom. The circle 18 is representative ofthe fuselage of an aircraft, the first 20 and second 22 lines arerepresentative of the wings of the aircraft, and the vertical line 24 isrepresentative of the tail of the aircraft.

A horizon line 26 extends across the circle defined by the sky arc 10and the earth arc 12, generally defining a cord thereof. The horizonline 26 extends approximately between the intersections of the sky arc10 and the earth arc 12. First 28 and second 30 pitch-angle indexmarkers extend from the ends of the horizon line 26 to the intersectionsof the sky arc 10 and earth arc 12.

With particular reference to FIG. 7, a bank angle indicator 32 comprisesa bank angle index mark 34 and a bank angle numeric display 36.

With particular reference to FIG. 8, a pitch numeric tape 38 comprises ascale 40 and a pointer or index 42 for indicating a particular numericalvalue upon the scale 40. The scale 40 scrolls in a fashion ofcontemporary tape readouts.

The symbology of FIG. 9 is actually an altimeter that incorporates avisual expression of the aircraft's relative position to the earth, afunction which allows the pilot to set a minimum altitude, and afunction which visually warns the pilot when he descends below thatminimum. In this sense, it is a terrain avoidance display and may beadapted to manual terrain following by the pilot's use of theinformation provided or by a pre-programmed software program.

A ground line 43 is formed generally parallel to the horizon line 26 andhas a vertical line 44 extending perpendicularly upwardly therefrom. Avertical rate indicator 46 is generally configured as an inverted V andmoves up and down with the ground line along vertical line 44 toindicate vertical rate.

Altitude numerical display 48 is formed generally upon ground line 43and preferably includes either an R to indicate radar altitude or a B toindicate barometric altitude, as selected.

With particular reference to FIG. 10, minimum altitude break 50 isgenerally configured as an X and is preferably superimposed over theaircraft symbol 14 to indicate that the aircraft is flying below aminimum desired altitude. Preferably, the minimum altitude break 50flashes so as to assure that the pilot's attention is captured thereby.

Heading and ground track indicator 52 comprises north index mark 54 andsouth index mark 56 diametrically opposed about circle 53. An N 58 isformed proximate the north index 54 and a S 60 is located proximate thesouth index 56. An aircraft heading index 62 remains stationary as thenorth 54 and south 56 indexes rotate about the circle 53 to indicate theheading of the aircraft. A numerical display 64 of aircraft heading isformed within the circle 53, preferably below the aircraft heading indexmark 62. A ground track correction numeric display 66 is formed belowthe numerical display of the heading 64.

Having described the first embodiment of the integrated flight controlindicator of the present invention in detail, it may be beneficial todiscuss the operation thereof. The sky arc 10 cooperates with the eartharc 12, so as to provide an immediately recognizable visual indicationof pitch. The relative proportion of the length of the sky arc 10 to theearth arc 12 is indicative of the pitch of the aircraft in a mannerwhich mimics actual cockpit observations of the sky and ground.

Thus, when the aircraft is flying straight and level, the length of thesky arc 10 is approximately equal to the length of the earth arc 12, asshown in FIG. 1. When the aircraft pitch is down, as when descending,the length of the earth arc 12 becomes greater than the length of thesky arc 10. The greater the downward pitch of the aircraft, the greaterthe relative proportion of the earth arc 12 to the sky arc 10.

Thus, when the plane is in a nose up attitude, the sky arc varies inlength from slightly greater than 180 degrees to 360 degrees and theearth arc varies in length from slightly less than 180 degrees to 0degrees. Similarly, when the aircraft is in a nose down attitude, thesky arc varies from slightly less than 180 degrees to 0 degrees and theearth arc varies in length from slightly greater than 180 degrees to 360degrees. When the aircraft is flying straight and level, the sky arc andthe earth arc are equal in length, i.e., 180 degrees each. When theaircraft is flying straight up, no earth arc 12 would be visible and theintegrated flight control indicator of the present invention wouldcomprise between 360 degrees of sky arc 10. During straight down flight,the sky arc 10 would not be visible and the integrated flight controlindicator would comprise 360 degrees of the earth arc 12.

This mimics the sky and earth conditions that a pilot views from thecockpit of an aircraft, wherein during a descent or pitch down attitude,a greater proportion of the ground would be visible as compared to skyand during an ascent or pitch up attitude of the aircraft, a greaterproportion of the sky would be visible as compared to the ground. Thus,the combination of the sky arc 10 and ground arc 12 of the presentinvention provides a natural and intuitive means for indicating pitch.

It is contemplated that the principles by which aircraft sensors candetect and produce electrical signals representative of various aircraftrelated parameters, e.g., air speed, altitude, pitch, roll, distance totarget, bearing to target, etc., are well known to one of ordinary skillin the art. In addition, it is further contemplated that the computerhardware and software which process and condition such electricalsignals for use to drive displays is also well known to one of ordinaryskill in the art. In this respect, aircraft sensors which detect andproduce electrical signals representative of aircraft pitch are wellknown in the art and may be processed according to well known methods inthe art in such a manner so as to be utilized by a display.

For example, when the aircraft is flying straight and level, it iscontemplated that sensors which are well known in the art may be used toproduce electrical signals indicative of such a zero pitch condition.These zero pitch signals may be processed according to well knownmethods in the art in such a manner so as to represent an input signalto the display. As mentioned above, when the aircraft is flying straightand level, the length of the sky arc 10 is approximately equal to thelength of the earth arc 12. Thus, in practice, it is contemplated thataircraft sensors would detect and produce electrical signalsrepresentative of the aircraft having a zero pitch. These electricalsignals are processed according well known methods such that the sky andearth arc display input signals correlate to those signals which causethe sky arc 10 and the earth arc 12 to be of approximately equal length.

The sky arc 10 and the earth arc 12 further cooperate to provide ageneral indication of roll or bank of the aircraft. The positions of theintersections of the sky arc 10 and the earth arc 12 rotate about thecircle defined thereby in proportion to the amount and direction of rollof the aircraft. A horizon line extends approximately between these twointersections, so as to provide a more definitive visual indication ofroll or bank, as discussed in detail below.

A more precise indication of pitch angle is provided by the pitchnumeric tape readout 40, preferably positioned immediately to the rightof the circle defined by the sky arc 10 and the earth arc 12. The pitchnumeric tape readout 40 displays pitch numerically in a fashion similarto that of a conventional tape readout wherein the numbers scroll up ordown, as necessary, and the particular number indicative of pitch isaligned with an index or pointer 42.

As mentioned above, bank or roll can visually be generally determined bythe orientation of the intersections of the sky arc 10 and the earth arc12. However, to provide a more readily discerned indication of bank orroll, a horizon line 26 extends across the circle defined by the sky arc10 and the earth arc 12. The horizon line 26 extends approximately fromone intersection of the sky arc 10 and earth arc 12 approximately to theother intersection thereof. Thus, as the aircraft banks or rolls, thehorizon line 26 moves in a direction opposite to that of the bank, asdoes the true horizon, and the aircraft symbol 14 remains stationaryrelative to the aircraft, thereby providing an indication of the degree,rate, and direction of bank or roll. Thus, the horizon line 26 moveswhile the aircraft symbol 14 remains stationary, thereby providing aninside-looking-out representation, as is traditional for aircraftcockpit instrumentation.

A more precise indication of bank or roll is optionally provided by bankangle indicator 32 (FIGS. 2 and 7). The bank angle indicator 32preferably defaults to the off or undisplayed position. When displayed,an index mark 34 is formed proximate that intersection of the sky arc 10and earth arc 12 on the side of the lowermost wing of the aircraft and anumeric display 32 indicative of the number of degrees of bank or rollis provided. Thus, the pilot may readily ascertain the direction anddegree of roll or bank.

The aircraft symbol 14 is locked to aircraft centerline such that as thesky arc 10, earth arc 12, and horizon line 26 rotate or move relativethereto. Thus, a readily ascertained visual indication of roll and pitchis provided thereby.

The aircraft symbol 14 will always maintain its orientation relative tothe pilot, while those indicia representative of the outside world,i.e., the sky arc 10, the earth arc 12, and the horizon line 26 allrotate relative thereto, in a manner which mimics observations of theseitems from the cockpit. Thus, the horizon line 26, for example, tilts tothe right or left in the same manner as does the true horizon observedfrom the cockpit. This provides an intuitive and easily understandablerepresentation of the roll of the aircraft.

According to the preferred embodiment of the present invention, the bankindex markers 28 and 30 extend from the two ends the horizon line 26 tothe two intersections of the sky arc 10 and earth arc 12. The bank angleindex markers 28 and 30 intersect the circle defined by the sky arc 10and earth arc 12 at right angles thereto. The bank angle index markers28 and 30 remain perpendicular to the sky arc 10 and earth arc 12regardless of the relative proportions of the sky arc 10 to the eartharc 12 and thus the angle between the horizon line 26 and the bank angleindex markers 28 and 30 varies as the pitch of the aircraft varies. Thisprovides a further visual indication of the pitch of the aircraft.

The effect of the bank angle index markers 28 and 30 is to exaggeratethe visible indication of pitch angle by reducing the area 11 enclosedby the sky arc 10, horizon line 26, and the bank angle index markers 28and 30 at a greater rate than would be the case absent the bank angleindex markers 28 and 30. That is, the bank angle index markers 28 and 30reduce the area 11 at a faster rate than would the horizon line 26alone, as the aircraft increases its pitch angle. This provides a muchmore dramatic visual indication of increasing pitch angle than would theuse of the horizon line 26 alone, thereby readily alerting the pilot toincreasing pitch angle. Of course, rapidly decreasing pitch angle ismade more apparent, as well.

The optional pitch dot 16 provides a more precise indication of pitch,particularly during straight and level flight when the horizon line 26is very close to the pitch dot 16. Thus, when the pitch dot 16 isdirectly superimposed upon the horizon line 26, as shown in FIG. 1, thenzero pitch is indicated.

Optionally, the ground line 43, formed generally parallel to the horizonline 26, is representative of the aircraft attitude. Thus, the groundline 43 will move downwardly as the aircraft ascends and will eventuallydisappear into the earth arc 12 when the aircraft reaches apredetermined altitude. Conversely, the ground line 43 moves upwardly,toward the aircraft symbol 14 as the aircraft descends and willapproximately touch the aircraft symbol 14 when the aircraft symbol 14is approximately at sea level or zero feet of altitude. Thus, thedistance between the aircraft symbol 14 and the ground line 43 isgenerally proportional to the distance between the aircraft itself andthe ground. Use of the ground line 43 in this manner facilitates terrainfollowing.

The ground line 43 is typically only displayed when the aircraftdescends below a pilot preset altitude. Thus, as the aircraft descendsbelow 2,000 feet, for example, the ground line appears at the bottom ofthe earth arc 12 and moves upward toward the aircraft symbol 14, alongwith the vertical rate indicator 46, as the aircraft continues todescend.

Further, according to the preferred embodiment of the present invention,a vertical rate indicator 46 moves vertically, so as to indicatevertical rate. Thus, as the aircraft ascends, the vertical rateindicator 46 and the ground line 43 move farther from the aircraftsymbol 14, and as the aircraft descends, the vertical rate indicator 46and the ground line 43 move closer to the aircraft symbol 14. Thevertical rate indicator 46 and the ground line 43 move at a raterepresentative of the actual vertical rate of the aircraft. The verticalrate indicator 14 always has its base on the ground line 43, i.e., movesalong with the ground line 43, and may generally be considered a partthereof.

The optional numeric display of either the radar altitude or thebarometric altitude is formed just above ground line 43, preferably tothe right of the vertical rate indicator 46. Either radar altitude, asindicated by an R, or barometric altitude as indicated by a B may bedisplayed, as desired.

A break-altitude symbol 50, if enabled, will be superimposed over theaircraft symbol 14 and will flash at any time that the aircraft is belowa pilot preset altitude. This pilot preset minimum altitude is generallyindicative of the lowest safe altitude at which the pilot has decidedthe aircraft may fly within a particular area, generally as determinedby the height of physical obstructions such as buildings, radio towers,mountains, etc. Thus, a display which quickly draws the pilot'sattention is provided thereby. The break-altitude symbol 50 preferablycomprises an X and preferably begins to flash when the uppermost tip ofthe vertical rate indicator 46 first touches the aircraft symbol 14,thereby indicating that a desired minimum altitude has been reached.

The optional heading and ground track indicator 52 provides a readilyascertained indication of both the aircraft's heading and ground track.Thus, as the aircraft changes direction, the numeric display of aircraftheading 64 changes, as well as the ground track numeric indication 66.Further, the north index 54 (best shown in FIG. 11) coupled with southindex 56, as well as the N 58 and S 60 symbols, rotate about the headingand ground track indicator 52 to provide a non-numeric visual indicationof heading. This indication is observed by merely noting the relativeposition of the aircraft centerline index 62 relative to the north index54. Rotation of the north 54 and south 56 indexes is particularly usefulin determining turn rate since the rate at which the north 54 and south56 indexes rotate about the heading and ground track indicator 52 isproportional to the actual turn rate of the aircraft.

Referring now to FIG. 12-15, a second embodiment of the integratedflight control indicator of the present invention is configured toutilize terrain following/avoidance equipment. According to the secondembodiment of the present invention, a stationary aircraft symbol 70 islocked to the aircraft centerline and preferably comprises a generallyhorizontal line 72 having a V-notch 74 formed proximate the centerthereof (as shown in FIG. 13).

As in the first embodiment of the present invention, a pitch numerictape 40 is utilized to indicate pitch angle. According to the secondembodiment of the present invention, the box surrounding the numerictape is eliminated. Those skilled in the art will appreciate thatvarious different representations of the pitch numeric tape are likewisesuitable.

With particular reference to FIG. 14, a flight path marker 77 generallycomprises a small circle 76 from which first 78 and second 80 horizontallines extend, from either side thereof, and from which vertical line 82extends, so as to generally resemble an aircraft. The flight path marker77 moves about within the circle defined by the sky arc 10 and earth arc12 as discussed below.

With particular reference to FIG. 15, the pitch numeric tape readout 90may be formed to either have a border, or not have a border, asdiscussed above.

Having described the second embodiment of the present invention, it maybe beneficial to discuss the operation thereof. According to the secondembodiment of the present invention, terrain following/avoidance isfacilitated by providing a stationary aircraft symbol 70 which is lockedto aircraft centerline and a moving flight path marker 77 which isdamped and constrained to stay within the circular boundary defined bythe sky arc 10 and the earth arc 12. The flight path marker 77 indicatesthe actual flight path of the aircraft so as to facilitate terrainfollowing/avoidance. The pilot merely maneuvers the aircraft so as toalign the flight path marker 77 with the stationary aircraft symbol 70.When the aircraft symbol 70 is aligned with the flight path marker 77,the aircraft is on course.

As shown in FIG. 12, the aircraft is low and to the left as compared tothe desired flight path. Thus, the pilot merely maneuvers the aircraftup and to the right such that the flight path marker 77 moves closer tothe stationary aircraft symbol 70, thereby attaining the desired flightpath.

The flight path marker (FPM) is present in all variations of the sky arcsymbology. It is always constrained within the circle formed by the skyarc and the earth arc. Within the circle, it is always free to move. Theflight path marker can be used in a number of ways, but its definedpurpose is to show the pilot the actual flight path of the aircraftrelative to the horizon. That information may, of course, be applied indifferent ways and used for various purposes under certain flightconditions. Often, it is not used for anything in particular by thepilot.

Referring now to FIGS. 16-19, a third embodiment of the integratedflight control indicator of the present invention is configured tofacilitate use with Instrument Landing Systems. According to the thirdembodiment of the present invention, the pitch numeric tape readout isreplaced with an angle-of-attack numeric tape readout 96 (also shown inFIG. 17), wherein the index or pointer preferably comprises a symbolrepresentative of the Greek letter alpha 98.

Additionally, the stationary aircraft symbol 70 of the second embodimentof the present invention is replaced with a heading and glide slopeindicator 100 (also shown in FIG. 19) which preferably comprises acircle having first 102 and second 104 lines extending horizontallytherefrom and a single line 106 extending vertically therefrom. A movingflight path marker 77, such as that utilized in all embodiments of thepresent invention, indicates deviation of the aircraft from the desiredflight path. An optional minimum approach altitude indicator 110 isincorporated into the glide scope indicator 100 and has a minimumapproach altitude numeric display 112 formed proximate thereto.Preferably, the distance between the minimum approach altitude indicator110 and the tip of the inverted V 46 is representative of the aircraft'saltitude above the minimum altitude. Thus, when the tip of the invertedV 46 touches the minimum approach altitude indicator 110, the aircraftis at minimum approach altitude.

As shown in FIG. 16, the pilot is at sufficient attitude that the groundline 43 has disappeared below the earth arc 12. The actual altitude ofthe aircraft as indicated by the barometric altimeter is 2,150 feet andthe minimum approach altitude for an instrument landing approach is1,200 feet. The aircraft is on course and descending at the desiredrate.

Optionally, the ground track indicator 52 displays ground track insteadof heading and cross-wind instead of ground track correction.

Having described the third embodiment of the integrated flight controlindicator of the present invention, it may be beneficial to describe theoperation thereof. To facilitate use of the integrated flight controlindicator of the present invention with Instrument Landing Systems, theaircraft symbol 70 of the second embodiment of the present invention isreplaced with a stationary heading and glide slope indicator 100 asdiscussed above. Thus, to utilize an Instrument Landing System, thepilot merely maneuvers the aircraft so as to maintain the flight pathmarker 77 within the heading and glide slope indicator 100 and such thatthe left 102 and right 104 index markers are generally aligned with theleft 78 and right 80 vertical lines extending from the flight pathmarker 77, so as to indicate that the aircraft is level or descending atthe correct rate. Observation of the minimum approach altitude indicator110 and the point of the inverted V 46 shows the pilot his altituderelative to the minimum permissible descent altitude below which thepilot either lands visually or initiates a missed approach procedure.

Referring now to FIG. 20, a simple circle may alternatively be utilizedas the aircraft symbol 200. Further, rather than using a R to indicateradar altitude, the letters AG, standing for above ground, may beutilized. This provides more distinct symbology with respect to the Butilized to indicate barometric altitude, so as to mitigate thepotential for confusion between the A and B, which are somewhat similarin appearance.

An optional air speed indicator 202 comprises a generally horizontalline 204 having a length generally representative of the maximum speedat which the aircraft is likely to travel. A stall indicator 206,indicated by a right-pointing arrow is disposed at the left side of theline 204, i.e., in the low speed region thereof, so as indicate thespeed at which a stall will occur in view of the present flightparameters, e.g., pitch angle, roll, air speed, altitude, etc., of theaircraft.

A maximum endurance indicator 208, represented by a right-angle linedescending from the air speed line 204, indicates the speed at which theaircraft is to be flown so as to remain in the air for the maximumlength of time. In a similar fashion, a maximum range indicator 216indicates the speed at which the aircraft is to be flown so as to attainthe maximum range. A left-pointing arrow defines the velocity not toexceed symbol 218, which is representative of the maximum velocity whichthe aircraft is structurally designed to withstand. The maximum turnrate is indicated by a circle which defines the maximum turn rateindicator 210. The present air speed symbol is comprised of the V 212and downward extending line 213. optionally, a numerical display 214 ofthe present air speed is provided just below the line 213. At thepilot's option, any or all of the following may be disabled so as tode-clutter the display as desired: the maximum endurance indicator 208,the maximum range indicator 216 and the maximum turn rate indicator 210.

Thus, the present air speed indicator 212 moves horizontally along theline 204, so as to indicate present air speed. Indicated air speedincreases as the present air speed indicator 212 moves from the left tothe right. The optional air speed indicator 202 of the present inventionprovides a quick indication of the present air speed with respect tothose particular air speeds which are considered critical to flight,e.g., stall speed, max turn rate, max range, max endurance, and velocitynot to exceed.

The heading and glide slope indicator of FIG. 19 is generallystationary, but may reposition itself, as required by the instrumentlanding approach parameters.

Referring now to FIG. 21, an optional fire control indicator 249comprises an arc 250, preferably disposed immediately to the left of thecircle defined by the sky arc 10 and the earth arc 12. The optional firecontrol indicator 249 provides various indications which aid a crewmember in the selection and use of aircraft weaponry. The integratedfire control indicator 249 comprises an arc 250 upon which are displayedthe pilot's aircraft 260 and a targeted aircraft 252. The distance alongthe arc 250 is proportional to the distance of the targeted aircraft 252from the pilot's own aircraft 260, and is also proportional to thedistance of a missile underway 258 from both the pilot's aircraft 260and the targeted aircraft 252. Thus, the missile underway symbol 258moves closer to the targeted aircraft symbol 252 as the actual missileapproaches its target.

According to the preferred embodiment of the present invention, range noescape, i.e., that range within which a hit is substantially guaranteed,is indicated by an open bracket 256, and the minimum range for firingthe weapon, i.e., the minimum safe distance from the targeted aircraftfor firing the selected weapon, is indicated by a closed bracket 254.The maximum firing range is indicated by the double line 262. All thesymbols on the arc 250 are dynamic and move in concert with the dynamicsof the fire control situation. As those skilled in the art willappreciate, various different symbols may be utilized to indicatedifferent types of missiles as well as whether or not those missiles arepresently selected or underway and may also be utilized to indicate thepresent status thereof, e.g., radar active, etc.

Optionally, an alpha-numeric display 264 of pertinent fire controlinformation is additionally provided, preferably immediately to the leftof the fire control arc 250. This information preferably comprises thespeed of the targeted aircraft, i.e., 525 nautical miles per hour, forexample; the bearing of the targeted aircraft relative to the aircraft,105 degrees, for example; the range from the aircraft to the targetedaircraft, 18.7 nautical miles, for example; and the altitude of thetargeted aircraft relative to the aircraft, minus 2,000 feet, forexample.

Weapons status is preferably also indicated in the alpha-numeric display264. For example, infrared missiles are preferably indicated by solidtriangles, radar missiles by circles, and a fired missile indicated byan X. The color of the symbol, the triangle, for example, may beutilized to indicated whether or not that missile has been selected andwhether or not the missile is armed. The number of rounds remaining fora gun, as indicated by G-350 (indicating 350 rounds remaining), may alsooptionally be provided.

According to the preferred embodiment of the present invention, arange/bearing line is also optionally provided 232. The range/bearingline comprises a range line 232, the length of which is indicative ofthe range to the target and the angle of which is indicative of thebearing of the target relative to the aircraft. The location of thetarget is provided by circle 234 and a symbol may optionally be enclosedwithin the interior 236 of the circle which is indicative of the type oftarget. The pointer 230 represents the heading of the aircraft so as toprovide a bearing reference for the range line 232. Additionally, thecircle formed by the sky arc and the earth arc may be used as a rangering. Range from the center of the circle to its edge is indicated innautical miles by a numeric 265.

According to the preferred embodiment of the present invention, variousfeatures of the integrated flight control indicator may be deactivatedor turned off, so as to reduce clutter, and thereby more readilyfacilitating perception of the desired indications for a particular typeof use. For example, the pitch tape may be disabled and pitchinformation then obtained directly from the sky arc portion of thedisplay, if desired.

The integrated flight control indicator of the present invention can bereduced in size substantially and still provide easily perceived flightcontrol indications. Thus, the flight control indicator may be shrunk,so as to minimize interference with a pilot's field of view.Additionally, the availability of such a reduced size integrated flightcontrol indicator facilitates its use in helmet-mounted displays,wherein the area available for such a display is strictly limited.

A computer preferably receives inputs from various different sensordevices, i.e., a pitch sensor, a roll sensor, etc., and generates adisplay which is representative of the outputs of said sensors inresponse to the received inputs. Those skilled in the art willappreciate that various different configurations of such computerizeddata acquisition and display system are suitable for use in the presentinvention.

Additionally, those skilled in the art will appreciate that variousdifferent types of displays, e.g., CRT, LED, projection, etc., aresuitable for use in the present invention.

Use of the integrated flight control indicator of the present inventionmakes changes, i.e., additions, deletions, and modifications, of thesymbology thereof easy to accomplish. For example, the nature of asymbol may easily be changed by merely modifying the computer programutilized to generate the symbol. Further, as the ability to acquireadditional information increases due to improvements in technology, thatnew information may easily be integrated into the present invention anddisplayed by merely modifying the software associated therewith.

Use of the integrated flight control indicator of the present inventioneliminates the need for a pilot to continuously scan a control panel,while simultaneously attempting to maintain surveillance of thesurrounding air space. Rather, all of the necessary flight controlindicators are contained within a small space which may be placed to theside of the pilot's normal field of view, so as not to interferesubstantially therewith.

It is understood that the exemplary integrated flight control indicatorof the present invention described herein and shown in the drawingsrepresents only a presently preferred embodiment of the invention.Indeed, various modifications and additions may be made to suchembodiments without departing from the spirit and scope of theinvention.

What is claimed is:
 1. An integrated flight control indicator forproviding visual information indicative of aircraft flight parameters,said integrated flight control indicator comprising:a) a sky arc; b) anearth arc visually distinguishable from said sky arc, said sky arc andsaid earth arc cooperating to generally define a circle, the relativelengths of said sky arc and said earth arc indicating pitch of theaircraft, the sky arc having a length greater than a length of the eartharc to indicate pitch up and the earth arc having a length greater thanthe length of the sky arc to indicate pitch down; c) a horizon lineextending approximately between two intersections of said sky arc andsaid earth arc so as to provide a visual indication of the roll of theaircraft; and d) bank angle markers extending radially inward from twointersections of said sky arc and said earth arc to two ends of saidhorizon line, the angle between said bank angle markers and said horizonline varying with the pitch of the aircraft such that during levelflight, the bank angle markers are co-linear therewith, during pitchdown the bank angle markers angle up from said horizon line, and duringpitch up, the bank angle markers angle down from said horizon line; e)wherein said sky arc and said earth arc provide a visual indicationsuitable for use in instrument panel displays, heads-up displays, andhelmet-mounted displays.
 2. The integrated flight control indicator asrecited in claim 1 further comprising a numerical display of a bankangle of the aircraft formed proximate the bank angle markercorresponding to a lowermost wing of the aircraft.
 3. An integratedflight control indicator for providing visual information indicative ofaircraft flight parameters, said integrated flight control indicatorcomprising:a) a sky arc; b) an earth arc visually distinguishable fromsaid sky arc; said sky arc and said earth arc cooperating to generallydefine a circle, the relative lengths of said sky arc and said earth arcindicating pitch of the aircraft, the sky arc having a length greaterthan a length of the earth arc to indicate pitch up and the earth archaving a length greater than the length of the sky arc to indicate pitchdown; and c) a break-altitude symbol formed within said circle definedby said sky arc and said earth arc to indicate that the aircraft hasdescended below a preset minimum altitude, the break-altitude symbolbeing configured to overlay an aircraft symbol; d) wherein said sky arcand said earth arc provide a visual indication suitable for use ininstrument panel displays, heads-up displays, and helmet-mounteddisplays.
 4. The integrated flight control indicator as recited in claim3, wherein said break-altitude symbol comprises an X.
 5. The integratedflight control indicator as recited in claim 4, wherein said X flashes.6. The integrated flight control indicator as recited in claim 3,wherein said break-altitude symbol remains and continues to flash untilthe aircraft ascends above the present minimum altitude.
 7. Anintegrated flight control indicator as recited in claim 3, furthercomprisingan air speed indicator, said air speed indicator comprising:i)a line having a length representative of a maximum speed of theaircraft; and ii) a present air speed symbol which moves along saidline, the position of the present air speed symbol along said lineindicating airspeed of the aircraft.
 8. The integrated flight controlindicator of claim 7 further comprising a stall speed symbol disposedalong said line, the position of the stall speed symbol along said lineindicating a stall speed of the aircraft.
 9. The integrated flightcontrol indicator of claim 7 further comprising a maximum endurancesymbol disposed along said line, the position of the maximum endurancesymbol along said line indicating a maximum endurance speed of theaircraft.
 10. The integrated flight control indicator of claim 7 furthercomprising a velocity not to exceed symbol along said line, the positionof the velocity not to exceed symbol along said line indicating avelocity not to exceed of the aircraft.